Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 1291 insertions, 0 deletions

diff --git a/drivers/net/tap.c b/drivers/net/tap.c
new file mode 100644
index 000000000..ff67d99de
--- /dev/null
+++ b/drivers/net/tap.c
@@ -0,0 +1,1291 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/etherdevice.h>
+#include <linux/if_tap.h>
+#include <linux/if_vlan.h>
+#include <linux/interrupt.h>
+#include <linux/nsproxy.h>
+#include <linux/compat.h>
+#include <linux/if_tun.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/cache.h>
+#include <linux/sched/signal.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/wait.h>
+#include <linux/cdev.h>
+#include <linux/idr.h>
+#include <linux/fs.h>
+#include <linux/uio.h>
+
+#include <net/gso.h>
+#include <net/net_namespace.h>
+#include <net/rtnetlink.h>
+#include <net/sock.h>
+#include <net/xdp.h>
+#include <linux/virtio_net.h>
+#include <linux/skb_array.h>
+
+#include "tun_vnet.h"
+
+#define TAP_IFFEATURES (IFF_VNET_HDR | IFF_MULTI_QUEUE)
+
+static struct proto tap_proto = {
+	.name = "tap",
+	.owner = THIS_MODULE,
+	.obj_size = sizeof(struct tap_queue),
+};
+
+#define TAP_NUM_DEVS (1U << MINORBITS)
+
+static LIST_HEAD(major_list);
+
+struct major_info {
+	struct rcu_head rcu;
+	dev_t major;
+	struct idr minor_idr;
+	spinlock_t minor_lock;
+	const char *device_name;
+	struct list_head next;
+};
+
+#define GOODCOPY_LEN 128
+
+static const struct proto_ops tap_socket_ops;
+
+#define RX_OFFLOADS (NETIF_F_GRO | NETIF_F_LRO)
+#define TAP_FEATURES (NETIF_F_GSO | NETIF_F_SG | NETIF_F_FRAGLIST)
+
+static struct tap_dev *tap_dev_get_rcu(const struct net_device *dev)
+{
+	return rcu_dereference(dev->rx_handler_data);
+}
+
+/*
+ * RCU usage:
+ * The tap_queue and the macvlan_dev are loosely coupled, the
+ * pointers from one to the other can only be read while rcu_read_lock
+ * or rtnl is held.
+ *
+ * Both the file and the macvlan_dev hold a reference on the tap_queue
+ * through sock_hold(&q->sk). When the macvlan_dev goes away first,
+ * q->vlan becomes inaccessible. When the files gets closed,
+ * tap_get_queue() fails.
+ *
+ * There may still be references to the struct sock inside of the
+ * queue from outbound SKBs, but these never reference back to the
+ * file or the dev. The data structure is freed through __sk_free
+ * when both our references and any pending SKBs are gone.
+ */
+
+static int tap_enable_queue(struct tap_dev *tap, struct file *file,
+			    struct tap_queue *q)
+{
+	int err = -EINVAL;
+
+	ASSERT_RTNL();
+
+	if (q->enabled)
+		goto out;
+
+	err = 0;
+	rcu_assign_pointer(tap->taps[tap->numvtaps], q);
+	q->queue_index = tap->numvtaps;
+	q->enabled = true;
+
+	tap->numvtaps++;
+out:
+	return err;
+}
+
+/* Requires RTNL */
+static int tap_set_queue(struct tap_dev *tap, struct file *file,
+			 struct tap_queue *q)
+{
+	if (tap->numqueues == MAX_TAP_QUEUES)
+		return -EBUSY;
+
+	rcu_assign_pointer(q->tap, tap);
+	rcu_assign_pointer(tap->taps[tap->numvtaps], q);
+	sock_hold(&q->sk);
+
+	q->file = file;
+	q->queue_index = tap->numvtaps;
+	q->enabled = true;
+	file->private_data = q;
+	list_add_tail(&q->next, &tap->queue_list);
+
+	tap->numvtaps++;
+	tap->numqueues++;
+
+	return 0;
+}
+
+static int tap_disable_queue(struct tap_queue *q)
+{
+	struct tap_dev *tap;
+	struct tap_queue *nq;
+
+	ASSERT_RTNL();
+	if (!q->enabled)
+		return -EINVAL;
+
+	tap = rtnl_dereference(q->tap);
+
+	if (tap) {
+		int index = q->queue_index;
+		BUG_ON(index >= tap->numvtaps);
+		nq = rtnl_dereference(tap->taps[tap->numvtaps - 1]);
+		nq->queue_index = index;
+
+		rcu_assign_pointer(tap->taps[index], nq);
+		RCU_INIT_POINTER(tap->taps[tap->numvtaps - 1], NULL);
+		q->enabled = false;
+
+		tap->numvtaps--;
+	}
+
+	return 0;
+}
+
+/*
+ * The file owning the queue got closed, give up both
+ * the reference that the files holds as well as the
+ * one from the macvlan_dev if that still exists.
+ *
+ * Using the spinlock makes sure that we don't get
+ * to the queue again after destroying it.
+ */
+static void tap_put_queue(struct tap_queue *q)
+{
+	struct tap_dev *tap;
+
+	rtnl_lock();
+	tap = rtnl_dereference(q->tap);
+
+	if (tap) {
+		if (q->enabled)
+			BUG_ON(tap_disable_queue(q));
+
+		tap->numqueues--;
+		RCU_INIT_POINTER(q->tap, NULL);
+		sock_put(&q->sk);
+		list_del_init(&q->next);
+	}
+
+	rtnl_unlock();
+
+	synchronize_rcu();
+	sock_put(&q->sk);
+}
+
+/*
+ * Select a queue based on the rxq of the device on which this packet
+ * arrived. If the incoming device is not mq, calculate a flow hash
+ * to select a queue. If all fails, find the first available queue.
+ * Cache vlan->numvtaps since it can become zero during the execution
+ * of this function.
+ */
+static struct tap_queue *tap_get_queue(struct tap_dev *tap,
+				       struct sk_buff *skb)
+{
+	struct tap_queue *queue = NULL;
+	/* Access to taps array is protected by rcu, but access to numvtaps
+	 * isn't. Below we use it to lookup a queue, but treat it as a hint
+	 * and validate that the result isn't NULL - in case we are
+	 * racing against queue removal.
+	 */
+	int numvtaps = READ_ONCE(tap->numvtaps);
+	__u32 rxq;
+
+	if (!numvtaps)
+		goto out;
+
+	if (numvtaps == 1)
+		goto single;
+
+	/* Check if we can use flow to select a queue */
+	rxq = skb_get_hash(skb);
+	if (rxq) {
+		queue = rcu_dereference(tap->taps[rxq % numvtaps]);
+		goto out;
+	}
+
+	if (likely(skb_rx_queue_recorded(skb))) {
+		rxq = skb_get_rx_queue(skb);
+
+		while (unlikely(rxq >= numvtaps))
+			rxq -= numvtaps;
+
+		queue = rcu_dereference(tap->taps[rxq]);
+		goto out;
+	}
+
+single:
+	queue = rcu_dereference(tap->taps[0]);
+out:
+	return queue;
+}
+
+/*
+ * The net_device is going away, give up the reference
+ * that it holds on all queues and safely set the pointer
+ * from the queues to NULL.
+ */
+void tap_del_queues(struct tap_dev *tap)
+{
+	struct tap_queue *q, *tmp;
+
+	ASSERT_RTNL();
+	list_for_each_entry_safe(q, tmp, &tap->queue_list, next) {
+		list_del_init(&q->next);
+		RCU_INIT_POINTER(q->tap, NULL);
+		if (q->enabled)
+			tap->numvtaps--;
+		tap->numqueues--;
+		sock_put(&q->sk);
+	}
+	BUG_ON(tap->numvtaps);
+	BUG_ON(tap->numqueues);
+	/* guarantee that any future tap_set_queue will fail */
+	tap->numvtaps = MAX_TAP_QUEUES;
+}
+EXPORT_SYMBOL_GPL(tap_del_queues);
+
+rx_handler_result_t tap_handle_frame(struct sk_buff **pskb)
+{
+	struct sk_buff *skb = *pskb;
+	struct net_device *dev = skb->dev;
+	struct tap_dev *tap;
+	struct tap_queue *q;
+	netdev_features_t features = TAP_FEATURES;
+	enum skb_drop_reason drop_reason;
+
+	tap = tap_dev_get_rcu(dev);
+	if (!tap)
+		return RX_HANDLER_PASS;
+
+	q = tap_get_queue(tap, skb);
+	if (!q)
+		return RX_HANDLER_PASS;
+
+	skb_push(skb, ETH_HLEN);
+
+	/* Apply the forward feature mask so that we perform segmentation
+	 * according to users wishes.  This only works if VNET_HDR is
+	 * enabled.
+	 */
+	if (q->flags & IFF_VNET_HDR)
+		features |= tap->tap_features;
+	if (netif_needs_gso(skb, features)) {
+		struct sk_buff *segs = __skb_gso_segment(skb, features, false);
+		struct sk_buff *next;
+
+		if (IS_ERR(segs)) {
+			drop_reason = SKB_DROP_REASON_SKB_GSO_SEG;
+			goto drop;
+		}
+
+		if (!segs) {
+			if (ptr_ring_produce(&q->ring, skb)) {
+				drop_reason = SKB_DROP_REASON_FULL_RING;
+				goto drop;
+			}
+			goto wake_up;
+		}
+
+		consume_skb(skb);
+		skb_list_walk_safe(segs, skb, next) {
+			skb_mark_not_on_list(skb);
+			if (ptr_ring_produce(&q->ring, skb)) {
+				drop_reason = SKB_DROP_REASON_FULL_RING;
+				kfree_skb_reason(skb, drop_reason);
+				kfree_skb_list_reason(next, drop_reason);
+				break;
+			}
+		}
+	} else {
+		/* If we receive a partial checksum and the tap side
+		 * doesn't support checksum offload, compute the checksum.
+		 * Note: it doesn't matter which checksum feature to
+		 *	  check, we either support them all or none.
+		 */
+		if (skb->ip_summed == CHECKSUM_PARTIAL &&
+		    !(features & NETIF_F_CSUM_MASK) &&
+		    skb_checksum_help(skb)) {
+			drop_reason = SKB_DROP_REASON_SKB_CSUM;
+			goto drop;
+		}
+		if (ptr_ring_produce(&q->ring, skb)) {
+			drop_reason = SKB_DROP_REASON_FULL_RING;
+			goto drop;
+		}
+	}
+
+wake_up:
+	wake_up_interruptible_poll(sk_sleep(&q->sk), EPOLLIN | EPOLLRDNORM | EPOLLRDBAND);
+	return RX_HANDLER_CONSUMED;
+
+drop:
+	/* Count errors/drops only here, thus don't care about args. */
+	if (tap->count_rx_dropped)
+		tap->count_rx_dropped(tap);
+	kfree_skb_reason(skb, drop_reason);
+	return RX_HANDLER_CONSUMED;
+}
+EXPORT_SYMBOL_GPL(tap_handle_frame);
+
+static struct major_info *tap_get_major(int major)
+{
+	struct major_info *tap_major;
+
+	list_for_each_entry_rcu(tap_major, &major_list, next) {
+		if (tap_major->major == major)
+			return tap_major;
+	}
+
+	return NULL;
+}
+
+int tap_get_minor(dev_t major, struct tap_dev *tap)
+{
+	int retval = -ENOMEM;
+	struct major_info *tap_major;
+
+	rcu_read_lock();
+	tap_major = tap_get_major(MAJOR(major));
+	if (!tap_major) {
+		retval = -EINVAL;
+		goto unlock;
+	}
+
+	spin_lock(&tap_major->minor_lock);
+	retval = idr_alloc(&tap_major->minor_idr, tap, 1, TAP_NUM_DEVS, GFP_ATOMIC);
+	if (retval >= 0) {
+		tap->minor = retval;
+	} else if (retval == -ENOSPC) {
+		netdev_err(tap->dev, "Too many tap devices\n");
+		retval = -EINVAL;
+	}
+	spin_unlock(&tap_major->minor_lock);
+
+unlock:
+	rcu_read_unlock();
+	return retval < 0 ? retval : 0;
+}
+EXPORT_SYMBOL_GPL(tap_get_minor);
+
+void tap_free_minor(dev_t major, struct tap_dev *tap)
+{
+	struct major_info *tap_major;
+
+	rcu_read_lock();
+	tap_major = tap_get_major(MAJOR(major));
+	if (!tap_major) {
+		goto unlock;
+	}
+
+	spin_lock(&tap_major->minor_lock);
+	if (tap->minor) {
+		idr_remove(&tap_major->minor_idr, tap->minor);
+		tap->minor = 0;
+	}
+	spin_unlock(&tap_major->minor_lock);
+
+unlock:
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(tap_free_minor);
+
+static struct tap_dev *dev_get_by_tap_file(int major, int minor)
+{
+	struct net_device *dev = NULL;
+	struct tap_dev *tap;
+	struct major_info *tap_major;
+
+	rcu_read_lock();
+	tap_major = tap_get_major(major);
+	if (!tap_major) {
+		tap = NULL;
+		goto unlock;
+	}
+
+	spin_lock(&tap_major->minor_lock);
+	tap = idr_find(&tap_major->minor_idr, minor);
+	if (tap) {
+		dev = tap->dev;
+		dev_hold(dev);
+	}
+	spin_unlock(&tap_major->minor_lock);
+
+unlock:
+	rcu_read_unlock();
+	return tap;
+}
+
+static void tap_sock_write_space(struct sock *sk)
+{
+	wait_queue_head_t *wqueue;
+
+	if (!sock_writeable(sk) ||
+	    !test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags))
+		return;
+
+	wqueue = sk_sleep(sk);
+	if (wqueue && waitqueue_active(wqueue))
+		wake_up_interruptible_poll(wqueue, EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND);
+}
+
+static void tap_sock_destruct(struct sock *sk)
+{
+	struct tap_queue *q = container_of(sk, struct tap_queue, sk);
+
+	ptr_ring_cleanup(&q->ring, __skb_array_destroy_skb);
+}
+
+static int tap_open(struct inode *inode, struct file *file)
+{
+	struct net *net = current->nsproxy->net_ns;
+	struct tap_dev *tap;
+	struct tap_queue *q;
+	int err = -ENODEV;
+
+	rtnl_lock();
+	tap = dev_get_by_tap_file(imajor(inode), iminor(inode));
+	if (!tap)
+		goto err;
+
+	err = -ENOMEM;
+	q = (struct tap_queue *)sk_alloc(net, AF_UNSPEC, GFP_KERNEL,
+					     &tap_proto, 0);
+	if (!q)
+		goto err;
+	if (ptr_ring_init(&q->ring, tap->dev->tx_queue_len, GFP_KERNEL)) {
+		sk_free(&q->sk);
+		goto err;
+	}
+
+	init_waitqueue_head(&q->sock.wq.wait);
+	q->sock.type = SOCK_RAW;
+	q->sock.state = SS_CONNECTED;
+	q->sock.file = file;
+	q->sock.ops = &tap_socket_ops;
+	sock_init_data_uid(&q->sock, &q->sk, current_fsuid());
+	q->sk.sk_write_space = tap_sock_write_space;
+	q->sk.sk_destruct = tap_sock_destruct;
+	q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP;
+	q->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
+
+	/*
+	 * so far only KVM virtio_net uses tap, enable zero copy between
+	 * guest kernel and host kernel when lower device supports zerocopy
+	 *
+	 * The macvlan supports zerocopy iff the lower device supports zero
+	 * copy so we don't have to look at the lower device directly.
+	 */
+	if ((tap->dev->features & NETIF_F_HIGHDMA) && (tap->dev->features & NETIF_F_SG))
+		sock_set_flag(&q->sk, SOCK_ZEROCOPY);
+
+	err = tap_set_queue(tap, file, q);
+	if (err) {
+		/* tap_sock_destruct() will take care of freeing ptr_ring */
+		goto err_put;
+	}
+
+	/* tap groks IOCB_NOWAIT just fine, mark it as such */
+	file->f_mode |= FMODE_NOWAIT;
+
+	dev_put(tap->dev);
+
+	rtnl_unlock();
+	return err;
+
+err_put:
+	sock_put(&q->sk);
+err:
+	if (tap)
+		dev_put(tap->dev);
+
+	rtnl_unlock();
+	return err;
+}
+
+static int tap_release(struct inode *inode, struct file *file)
+{
+	struct tap_queue *q = file->private_data;
+	tap_put_queue(q);
+	return 0;
+}
+
+static __poll_t tap_poll(struct file *file, poll_table *wait)
+{
+	struct tap_queue *q = file->private_data;
+	__poll_t mask = EPOLLERR;
+
+	if (!q)
+		goto out;
+
+	mask = 0;
+	poll_wait(file, &q->sock.wq.wait, wait);
+
+	if (!ptr_ring_empty(&q->ring))
+		mask |= EPOLLIN | EPOLLRDNORM;
+
+	if (sock_writeable(&q->sk) ||
+	    (!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &q->sock.flags) &&
+	     sock_writeable(&q->sk)))
+		mask |= EPOLLOUT | EPOLLWRNORM;
+
+out:
+	return mask;
+}
+
+static inline struct sk_buff *tap_alloc_skb(struct sock *sk, size_t prepad,
+					    size_t len, size_t linear,
+						int noblock, int *err)
+{
+	struct sk_buff *skb;
+
+	/* Under a page?  Don't bother with paged skb. */
+	if (prepad + len < PAGE_SIZE || !linear)
+		linear = len;
+
+	if (len - linear > MAX_SKB_FRAGS * (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER))
+		linear = len - MAX_SKB_FRAGS * (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER);
+	skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
+				   err, PAGE_ALLOC_COSTLY_ORDER);
+	if (!skb)
+		return NULL;
+
+	skb_reserve(skb, prepad);
+	skb_put(skb, linear);
+	skb->data_len = len - linear;
+	skb->len += len - linear;
+
+	return skb;
+}
+
+/* Neighbour code has some assumptions on HH_DATA_MOD alignment */
+#define TAP_RESERVE HH_DATA_OFF(ETH_HLEN)
+
+/* Get packet from user space buffer */
+static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,
+			    struct iov_iter *from, int noblock)
+{
+	int good_linear = SKB_MAX_HEAD(TAP_RESERVE);
+	struct sk_buff *skb;
+	struct tap_dev *tap;
+	unsigned long total_len = iov_iter_count(from);
+	unsigned long len = total_len;
+	int err;
+	struct virtio_net_hdr vnet_hdr = { 0 };
+	int vnet_hdr_len = 0;
+	int hdr_len = 0;
+	int copylen = 0;
+	int depth;
+	bool zerocopy = false;
+	size_t linear;
+	enum skb_drop_reason drop_reason;
+
+	if (q->flags & IFF_VNET_HDR) {
+		vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
+
+		hdr_len = tun_vnet_hdr_get(vnet_hdr_len, q->flags, from, &vnet_hdr);
+		if (hdr_len < 0) {
+			err = hdr_len;
+			goto err;
+		}
+
+		len -= vnet_hdr_len;
+	}
+
+	err = -EINVAL;
+	if (unlikely(len < ETH_HLEN))
+		goto err;
+
+	if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) {
+		struct iov_iter i;
+
+		copylen = clamp(hdr_len ?: GOODCOPY_LEN, ETH_HLEN, good_linear);
+		linear = copylen;
+		i = *from;
+		iov_iter_advance(&i, copylen);
+		if (iov_iter_npages(&i, INT_MAX) <= MAX_SKB_FRAGS)
+			zerocopy = true;
+	}
+
+	if (!zerocopy) {
+		copylen = len;
+		linear = clamp(hdr_len, ETH_HLEN, good_linear);
+	}
+
+	skb = tap_alloc_skb(&q->sk, TAP_RESERVE, copylen,
+			    linear, noblock, &err);
+	if (!skb)
+		goto err;
+
+	if (zerocopy)
+		err = zerocopy_sg_from_iter(skb, from);
+	else
+		err = skb_copy_datagram_from_iter(skb, 0, from, len);
+
+	if (err) {
+		drop_reason = SKB_DROP_REASON_SKB_UCOPY_FAULT;
+		goto err_kfree;
+	}
+
+	skb_set_network_header(skb, ETH_HLEN);
+	skb_reset_mac_header(skb);
+	skb->protocol = eth_hdr(skb)->h_proto;
+
+	rcu_read_lock();
+	tap = rcu_dereference(q->tap);
+	if (!tap) {
+		kfree_skb(skb);
+		rcu_read_unlock();
+		return total_len;
+	}
+	skb->dev = tap->dev;
+
+	if (vnet_hdr_len) {
+		err = tun_vnet_hdr_to_skb(q->flags, skb, &vnet_hdr);
+		if (err) {
+			rcu_read_unlock();
+			drop_reason = SKB_DROP_REASON_DEV_HDR;
+			goto err_kfree;
+		}
+	}
+
+	skb_probe_transport_header(skb);
+
+	/* Move network header to the right position for VLAN tagged packets */
+	if (eth_type_vlan(skb->protocol) &&
+	    vlan_get_protocol_and_depth(skb, skb->protocol, &depth) != 0)
+		skb_set_network_header(skb, depth);
+
+	/* copy skb_ubuf_info for callback when skb has no error */
+	if (zerocopy) {
+		skb_zcopy_init(skb, msg_control);
+	} else if (msg_control) {
+		struct ubuf_info *uarg = msg_control;
+		uarg->ops->complete(NULL, uarg, false);
+	}
+
+	dev_queue_xmit(skb);
+	rcu_read_unlock();
+	return total_len;
+
+err_kfree:
+	kfree_skb_reason(skb, drop_reason);
+
+err:
+	rcu_read_lock();
+	tap = rcu_dereference(q->tap);
+	if (tap && tap->count_tx_dropped)
+		tap->count_tx_dropped(tap);
+	rcu_read_unlock();
+
+	return err;
+}
+
+static ssize_t tap_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct tap_queue *q = file->private_data;
+	int noblock = 0;
+
+	if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
+		noblock = 1;
+
+	return tap_get_user(q, NULL, from, noblock);
+}
+
+/* Put packet to the user space buffer */
+static ssize_t tap_put_user(struct tap_queue *q,
+			    const struct sk_buff *skb,
+			    struct iov_iter *iter)
+{
+	int ret;
+	int vnet_hdr_len = 0;
+	int vlan_offset = 0;
+	int total;
+
+	if (q->flags & IFF_VNET_HDR) {
+		struct virtio_net_hdr vnet_hdr;
+
+		vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
+
+		ret = tun_vnet_hdr_from_skb(q->flags, NULL, skb, &vnet_hdr);
+		if (ret)
+			return ret;
+
+		ret = tun_vnet_hdr_put(vnet_hdr_len, iter, &vnet_hdr);
+		if (ret)
+			return ret;
+	}
+	total = vnet_hdr_len;
+	total += skb->len;
+
+	if (skb_vlan_tag_present(skb)) {
+		struct {
+			__be16 h_vlan_proto;
+			__be16 h_vlan_TCI;
+		} veth;
+		veth.h_vlan_proto = skb->vlan_proto;
+		veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
+
+		vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
+		total += VLAN_HLEN;
+
+		ret = skb_copy_datagram_iter(skb, 0, iter, vlan_offset);
+		if (ret || !iov_iter_count(iter))
+			goto done;
+
+		ret = copy_to_iter(&veth, sizeof(veth), iter);
+		if (ret != sizeof(veth) || !iov_iter_count(iter))
+			goto done;
+	}
+
+	ret = skb_copy_datagram_iter(skb, vlan_offset, iter,
+				     skb->len - vlan_offset);
+
+done:
+	return ret ? ret : total;
+}
+
+static ssize_t tap_do_read(struct tap_queue *q,
+			   struct iov_iter *to,
+			   int noblock, struct sk_buff *skb)
+{
+	DEFINE_WAIT(wait);
+	ssize_t ret = 0;
+
+	if (!iov_iter_count(to)) {
+		kfree_skb(skb);
+		return 0;
+	}
+
+	if (skb)
+		goto put;
+
+	while (1) {
+		if (!noblock)
+			prepare_to_wait(sk_sleep(&q->sk), &wait,
+					TASK_INTERRUPTIBLE);
+
+		/* Read frames from the queue */
+		skb = ptr_ring_consume(&q->ring);
+		if (skb)
+			break;
+		if (noblock) {
+			ret = -EAGAIN;
+			break;
+		}
+		if (signal_pending(current)) {
+			ret = -ERESTARTSYS;
+			break;
+		}
+		/* Nothing to read, let's sleep */
+		schedule();
+	}
+	if (!noblock)
+		finish_wait(sk_sleep(&q->sk), &wait);
+
+put:
+	if (skb) {
+		ret = tap_put_user(q, skb, to);
+		if (unlikely(ret < 0))
+			kfree_skb(skb);
+		else
+			consume_skb(skb);
+	}
+	return ret;
+}
+
+static ssize_t tap_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct file *file = iocb->ki_filp;
+	struct tap_queue *q = file->private_data;
+	ssize_t len = iov_iter_count(to), ret;
+	int noblock = 0;
+
+	if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
+		noblock = 1;
+
+	ret = tap_do_read(q, to, noblock, NULL);
+	ret = min_t(ssize_t, ret, len);
+	if (ret > 0)
+		iocb->ki_pos = ret;
+	return ret;
+}
+
+static struct tap_dev *tap_get_tap_dev(struct tap_queue *q)
+{
+	struct tap_dev *tap;
+
+	ASSERT_RTNL();
+	tap = rtnl_dereference(q->tap);
+	if (tap)
+		dev_hold(tap->dev);
+
+	return tap;
+}
+
+static void tap_put_tap_dev(struct tap_dev *tap)
+{
+	dev_put(tap->dev);
+}
+
+static int tap_ioctl_set_queue(struct file *file, unsigned int flags)
+{
+	struct tap_queue *q = file->private_data;
+	struct tap_dev *tap;
+	int ret;
+
+	tap = tap_get_tap_dev(q);
+	if (!tap)
+		return -EINVAL;
+
+	if (flags & IFF_ATTACH_QUEUE)
+		ret = tap_enable_queue(tap, file, q);
+	else if (flags & IFF_DETACH_QUEUE)
+		ret = tap_disable_queue(q);
+	else
+		ret = -EINVAL;
+
+	tap_put_tap_dev(tap);
+	return ret;
+}
+
+static int set_offload(struct tap_queue *q, unsigned long arg)
+{
+	struct tap_dev *tap;
+	netdev_features_t features;
+	netdev_features_t feature_mask = 0;
+
+	tap = rtnl_dereference(q->tap);
+	if (!tap)
+		return -ENOLINK;
+
+	features = tap->dev->features;
+
+	if (arg & TUN_F_CSUM) {
+		feature_mask = NETIF_F_HW_CSUM;
+
+		if (arg & (TUN_F_TSO4 | TUN_F_TSO6)) {
+			if (arg & TUN_F_TSO_ECN)
+				feature_mask |= NETIF_F_TSO_ECN;
+			if (arg & TUN_F_TSO4)
+				feature_mask |= NETIF_F_TSO;
+			if (arg & TUN_F_TSO6)
+				feature_mask |= NETIF_F_TSO6;
+		}
+
+		/* TODO: for now USO4 and USO6 should work simultaneously */
+		if ((arg & (TUN_F_USO4 | TUN_F_USO6)) == (TUN_F_USO4 | TUN_F_USO6))
+			feature_mask |= NETIF_F_GSO_UDP_L4;
+	}
+
+	/* tun/tap driver inverts the usage for TSO offloads, where
+	 * setting the TSO bit means that the userspace wants to
+	 * accept TSO frames and turning it off means that user space
+	 * does not support TSO.
+	 * For tap, we have to invert it to mean the same thing.
+	 * When user space turns off TSO, we turn off GSO/LRO so that
+	 * user-space will not receive TSO frames.
+	 */
+	if (feature_mask & (NETIF_F_TSO | NETIF_F_TSO6 | NETIF_F_GSO_UDP_L4))
+		features |= RX_OFFLOADS;
+	else
+		features &= ~RX_OFFLOADS;
+
+	/* tap_features are the same as features on tun/tap and
+	 * reflect user expectations.
+	 */
+	tap->tap_features = feature_mask;
+	if (tap->update_features)
+		tap->update_features(tap, features);
+
+	return 0;
+}
+
+/*
+ * provide compatibility with generic tun/tap interface
+ */
+static long tap_ioctl(struct file *file, unsigned int cmd,
+		      unsigned long arg)
+{
+	struct tap_queue *q = file->private_data;
+	struct tap_dev *tap;
+	void __user *argp = (void __user *)arg;
+	struct sockaddr_storage ss = {};
+	struct ifreq __user *ifr = argp;
+	unsigned int __user *up = argp;
+	unsigned short u;
+	int __user *sp = argp;
+	int s;
+	int ret;
+
+	switch (cmd) {
+	case TUNSETIFF:
+		/* ignore the name, just look at flags */
+		if (get_user(u, &ifr->ifr_flags))
+			return -EFAULT;
+
+		ret = 0;
+		if ((u & ~TAP_IFFEATURES) != (IFF_NO_PI | IFF_TAP))
+			ret = -EINVAL;
+		else
+			q->flags = (q->flags & ~TAP_IFFEATURES) | u;
+
+		return ret;
+
+	case TUNGETIFF:
+		rtnl_lock();
+		tap = tap_get_tap_dev(q);
+		if (!tap) {
+			rtnl_unlock();
+			return -ENOLINK;
+		}
+
+		ret = 0;
+		u = q->flags;
+		if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) ||
+		    put_user(u, &ifr->ifr_flags))
+			ret = -EFAULT;
+		tap_put_tap_dev(tap);
+		rtnl_unlock();
+		return ret;
+
+	case TUNSETQUEUE:
+		if (get_user(u, &ifr->ifr_flags))
+			return -EFAULT;
+		rtnl_lock();
+		ret = tap_ioctl_set_queue(file, u);
+		rtnl_unlock();
+		return ret;
+
+	case TUNGETFEATURES:
+		if (put_user(IFF_TAP | IFF_NO_PI | TAP_IFFEATURES, up))
+			return -EFAULT;
+		return 0;
+
+	case TUNSETSNDBUF:
+		if (get_user(s, sp))
+			return -EFAULT;
+		if (s <= 0)
+			return -EINVAL;
+
+		q->sk.sk_sndbuf = s;
+		return 0;
+
+	case TUNSETOFFLOAD:
+		/* let the user check for future flags */
+		if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
+			    TUN_F_TSO_ECN | TUN_F_UFO |
+			    TUN_F_USO4 | TUN_F_USO6))
+			return -EINVAL;
+
+		rtnl_lock();
+		ret = set_offload(q, arg);
+		rtnl_unlock();
+		return ret;
+
+	case SIOCGIFHWADDR:
+		rtnl_lock();
+		tap = tap_get_tap_dev(q);
+		if (!tap) {
+			rtnl_unlock();
+			return -ENOLINK;
+		}
+		ret = 0;
+		netif_get_mac_address((struct sockaddr *)&ss, dev_net(tap->dev),
+				      tap->dev->name);
+		if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) ||
+		    copy_to_user(&ifr->ifr_hwaddr, &ss, sizeof(ifr->ifr_hwaddr)))
+			ret = -EFAULT;
+		tap_put_tap_dev(tap);
+		rtnl_unlock();
+		return ret;
+
+	case SIOCSIFHWADDR:
+		if (copy_from_user(&ss, &ifr->ifr_hwaddr, sizeof(ifr->ifr_hwaddr)))
+			return -EFAULT;
+		rtnl_lock();
+		tap = tap_get_tap_dev(q);
+		if (!tap) {
+			rtnl_unlock();
+			return -ENOLINK;
+		}
+		if (tap->dev->addr_len > sizeof(ifr->ifr_hwaddr))
+			ret = -EINVAL;
+		else
+			ret = dev_set_mac_address_user(tap->dev, &ss, NULL);
+		tap_put_tap_dev(tap);
+		rtnl_unlock();
+		return ret;
+
+	default:
+		return tun_vnet_ioctl(&q->vnet_hdr_sz, &q->flags, cmd, sp);
+	}
+}
+
+static const struct file_operations tap_fops = {
+	.owner		= THIS_MODULE,
+	.open		= tap_open,
+	.release	= tap_release,
+	.read_iter	= tap_read_iter,
+	.write_iter	= tap_write_iter,
+	.poll		= tap_poll,
+	.unlocked_ioctl	= tap_ioctl,
+	.compat_ioctl	= compat_ptr_ioctl,
+};
+
+static int tap_get_user_xdp(struct tap_queue *q, struct xdp_buff *xdp)
+{
+	struct virtio_net_hdr *gso = xdp->data_hard_start;
+	int buflen = xdp->frame_sz;
+	int vnet_hdr_len = 0;
+	struct tap_dev *tap;
+	struct sk_buff *skb;
+	int err, depth;
+
+	if (unlikely(xdp->data_end - xdp->data < ETH_HLEN)) {
+		put_page(virt_to_head_page(xdp->data));
+		err = -EINVAL;
+		goto err;
+	}
+
+	if (q->flags & IFF_VNET_HDR)
+		vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
+
+	skb = build_skb(xdp->data_hard_start, buflen);
+	if (!skb) {
+		put_page(virt_to_head_page(xdp->data));
+		err = -ENOMEM;
+		goto err;
+	}
+
+	skb_reserve(skb, xdp->data - xdp->data_hard_start);
+	skb_put(skb, xdp->data_end - xdp->data);
+
+	skb_set_network_header(skb, ETH_HLEN);
+	skb_reset_mac_header(skb);
+	skb->protocol = eth_hdr(skb)->h_proto;
+
+	rcu_read_lock();
+	tap = rcu_dereference(q->tap);
+	if (!tap) {
+		kfree_skb(skb);
+		rcu_read_unlock();
+		return 0;
+	}
+	skb->dev = tap->dev;
+
+	if (vnet_hdr_len) {
+		err = tun_vnet_hdr_to_skb(q->flags, skb, gso);
+		if (err) {
+			rcu_read_unlock();
+			goto err_kfree;
+		}
+	}
+
+	skb_probe_transport_header(skb);
+
+	/* Move network header to the right position for VLAN tagged packets */
+	if (eth_type_vlan(skb->protocol) &&
+	    vlan_get_protocol_and_depth(skb, skb->protocol, &depth) != 0)
+		skb_set_network_header(skb, depth);
+
+	dev_queue_xmit(skb);
+	rcu_read_unlock();
+
+	return 0;
+
+err_kfree:
+	kfree_skb(skb);
+err:
+	rcu_read_lock();
+	tap = rcu_dereference(q->tap);
+	if (tap && tap->count_tx_dropped)
+		tap->count_tx_dropped(tap);
+	rcu_read_unlock();
+	return err;
+}
+
+static int tap_sendmsg(struct socket *sock, struct msghdr *m,
+		       size_t total_len)
+{
+	struct tap_queue *q = container_of(sock, struct tap_queue, sock);
+	struct tun_msg_ctl *ctl = m->msg_control;
+	struct xdp_buff *xdp;
+	int i;
+
+	if (m->msg_controllen == sizeof(struct tun_msg_ctl) &&
+	    ctl && ctl->type == TUN_MSG_PTR) {
+		for (i = 0; i < ctl->num; i++) {
+			xdp = &((struct xdp_buff *)ctl->ptr)[i];
+			tap_get_user_xdp(q, xdp);
+		}
+		return 0;
+	}
+
+	return tap_get_user(q, ctl ? ctl->ptr : NULL, &m->msg_iter,
+			    m->msg_flags & MSG_DONTWAIT);
+}
+
+static int tap_recvmsg(struct socket *sock, struct msghdr *m,
+		       size_t total_len, int flags)
+{
+	struct tap_queue *q = container_of(sock, struct tap_queue, sock);
+	struct sk_buff *skb = m->msg_control;
+	int ret;
+	if (flags & ~(MSG_DONTWAIT|MSG_TRUNC)) {
+		kfree_skb(skb);
+		return -EINVAL;
+	}
+	ret = tap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT, skb);
+	if (ret > total_len) {
+		m->msg_flags |= MSG_TRUNC;
+		ret = flags & MSG_TRUNC ? ret : total_len;
+	}
+	return ret;
+}
+
+static int tap_peek_len(struct socket *sock)
+{
+	struct tap_queue *q = container_of(sock, struct tap_queue,
+					       sock);
+	return PTR_RING_PEEK_CALL(&q->ring, __skb_array_len_with_tag);
+}
+
+/* Ops structure to mimic raw sockets with tun */
+static const struct proto_ops tap_socket_ops = {
+	.sendmsg = tap_sendmsg,
+	.recvmsg = tap_recvmsg,
+	.peek_len = tap_peek_len,
+};
+
+/* Get an underlying socket object from tun file.  Returns error unless file is
+ * attached to a device.  The returned object works like a packet socket, it
+ * can be used for sock_sendmsg/sock_recvmsg.  The caller is responsible for
+ * holding a reference to the file for as long as the socket is in use. */
+struct socket *tap_get_socket(struct file *file)
+{
+	struct tap_queue *q;
+	if (file->f_op != &tap_fops)
+		return ERR_PTR(-EINVAL);
+	q = file->private_data;
+	if (!q)
+		return ERR_PTR(-EBADFD);
+	return &q->sock;
+}
+EXPORT_SYMBOL_GPL(tap_get_socket);
+
+struct ptr_ring *tap_get_ptr_ring(struct file *file)
+{
+	struct tap_queue *q;
+
+	if (file->f_op != &tap_fops)
+		return ERR_PTR(-EINVAL);
+	q = file->private_data;
+	if (!q)
+		return ERR_PTR(-EBADFD);
+	return &q->ring;
+}
+EXPORT_SYMBOL_GPL(tap_get_ptr_ring);
+
+int tap_queue_resize(struct tap_dev *tap)
+{
+	struct net_device *dev = tap->dev;
+	struct tap_queue *q;
+	struct ptr_ring **rings;
+	int n = tap->numqueues;
+	int ret, i = 0;
+
+	rings = kmalloc_objs(*rings, n);
+	if (!rings)
+		return -ENOMEM;
+
+	list_for_each_entry(q, &tap->queue_list, next)
+		rings[i++] = &q->ring;
+
+	ret = ptr_ring_resize_multiple_bh(rings, n,
+					  dev->tx_queue_len, GFP_KERNEL,
+					  __skb_array_destroy_skb);
+
+	kfree(rings);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(tap_queue_resize);
+
+static int tap_list_add(dev_t major, const char *device_name)
+{
+	struct major_info *tap_major;
+
+	tap_major = kzalloc_obj(*tap_major, GFP_ATOMIC);
+	if (!tap_major)
+		return -ENOMEM;
+
+	tap_major->major = MAJOR(major);
+
+	idr_init(&tap_major->minor_idr);
+	spin_lock_init(&tap_major->minor_lock);
+
+	tap_major->device_name = device_name;
+
+	list_add_tail_rcu(&tap_major->next, &major_list);
+	return 0;
+}
+
+int tap_create_cdev(struct cdev *tap_cdev, dev_t *tap_major,
+		    const char *device_name, struct module *module)
+{
+	int err;
+
+	err = alloc_chrdev_region(tap_major, 0, TAP_NUM_DEVS, device_name);
+	if (err)
+		goto out1;
+
+	cdev_init(tap_cdev, &tap_fops);
+	tap_cdev->owner = module;
+	err = cdev_add(tap_cdev, *tap_major, TAP_NUM_DEVS);
+	if (err)
+		goto out2;
+
+	err =  tap_list_add(*tap_major, device_name);
+	if (err)
+		goto out3;
+
+	return 0;
+
+out3:
+	cdev_del(tap_cdev);
+out2:
+	unregister_chrdev_region(*tap_major, TAP_NUM_DEVS);
+out1:
+	return err;
+}
+EXPORT_SYMBOL_GPL(tap_create_cdev);
+
+void tap_destroy_cdev(dev_t major, struct cdev *tap_cdev)
+{
+	struct major_info *tap_major, *tmp;
+
+	cdev_del(tap_cdev);
+	unregister_chrdev_region(major, TAP_NUM_DEVS);
+	list_for_each_entry_safe(tap_major, tmp, &major_list, next) {
+		if (tap_major->major == MAJOR(major)) {
+			idr_destroy(&tap_major->minor_idr);
+			list_del_rcu(&tap_major->next);
+			kfree_rcu(tap_major, rcu);
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(tap_destroy_cdev);
+
+MODULE_DESCRIPTION("Common library for drivers implementing the TAP interface");
+MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>");
+MODULE_AUTHOR("Sainath Grandhi <sainath.grandhi@intel.com>");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("NETDEV_INTERNAL");